Diverter assembly for fuel filter

Abstract

The base assembly of a fuel filter assembly includes a base member and a bimetallic disc. The base member has a fuel supply inlet for receiving a flow of new fuel from a fuel tank and an inlet plenum in fluid communication with the fuel supply inlet and the filter cartridge. The base member also has an excess fuel inlet for receiving a flow of excess fuel from the fuel injection pump, an excess fuel outlet in fluid communication with the fuel tank, and a fuel passage providing fluid communication between the excess fuel inlet and the excess fuel outlet. The bimetallic disc is disposed in the fuel passage adjacent an opening in the wall separating the fuel passage from the inlet plenum. The edge portion of the bimetallic disc is flexed away from the wall to open the opening when the temperature of the excess fuel is below a predetermined value, warming the new fuel to prevent formation of wax crystals. The bimetallic disc is flexed to engage the wall, closing the opening, when the temperature of the excess fuel is above the predetermined value. When the opening is open, the differential pressure between the excess fuel and the new fuel causes the excess fuel to flow from the fuel passage into the inlet plenum and prevents backflow of new fuel through the opening.

What is claimed is: 
     
       1. A fuel filter assembly comprising: a base comprising a base member having a fuel supply inlet for receiving a flow of new fuel having a pressure Pn, a fuel supply outlet, an inlet plenum in fluid communication with the fuel supply inlet, first and second conduits in fluid communication with the inlet plenum and fuel supply outlet, respectively, an excess fuel inlet for receiving a flow of excess fuel having a temperature Te and a pressure Pe, the pressure of the excess fuel Pe being greater than the pressure of the new fuel Pn, an excess fuel outlet, a fuel passage providing fluid communication between the excess fuel inlet and the excess fuel outlet, separator means for separating the fuel passage from the inlet plenum, the separator means defining an opening providing fluid communication between the fuel passage and the inlet plenum,   a bimetallic disc disposed in the fuel passage adjacent the opening, the bimetallic disc having a perimeter defining an edge portion, the perimeter of the bimetallic disc being flexed away from the separator means when the temperature of the excess fuel Te is below a predetermined value Tp, the perimeter of the bimetallic disc being flexed toward the separator means when the temperature of the excess fuel is above the predetermined value wherein the edge portion of the bimetallic disc engages the separator means to seal the opening; and     a filter cartridge engaged with the base, the filter cartridge defining a flow path providing fluid communication between the first and second conduits of the base member, the filter cartridge having at least one filter element which traverses the flow path;   wherein the pressure of the excess fuel and the pressure of the new fuel define a differential pressure across the separator means, the differential pressure causing the excess fuel to flow from the fuel passage of the base member into the inlet plenum of the base member when the perimeter of the bimetallic disc is flexed away from the separator means and preventing flow of new fuel from the inlet plenum of the base member into the fuel passage of the base member.   
     
     
       2. The filter assembly of claim 1 wherein the base further comprises means for limiting flow, disposed in the fuel passage of the base member intermediate the opening and the excess fuel outlet. 
     
     
       3. The filter assembly of claim 2 wherein the means for limiting flow comprises a check valve. 
     
     
       4. The filter assembly of claim 1 wherein the opening comprises a throat segment adjacent the fuel passage of the base member, the throat segment having an outboard end adjacent said fuel passage and an inboard end adjacent said inlet plenum each having a diameter, the diameter of the outboard end of the throat segment being greater than the diameter of the inboard end of the throat segment, wherein the throat segment has a chamfered interior surface. 
     
     
       5. The filter assembly of claim 4 wherein the chamfered interior surface defines first and second oppositely disposed sides, the first and second sides defining an angle of substantially 118°. 
     
     
       6. The filter assembly of claim 4 wherein the diameter of the outboard end of the throat segment is substantially equal to 0.55 inches and the diameter of the inboard end of the throat segment is substantially equal to 0.34 inches. 
     
     
       7. The filter assembly of claim 6 wherein the bimetallic disc has an outside diameter substantially equal to 0.62 inches. 
     
     
       8. The filter assembly of claim 1 wherein the bimetallic disc and the separator means of the base member define a gap when the perimeter of the bimetallic disc is flexed away from the separator means, the gap having a width substantially equal to 0.02 inches. 
     
     
       9. The filter assembly of claim 1 wherein the base further comprises a mounting port and a mounting plug having a body member and a positioning member, the body member being removably mounted in the mounting port, the bimetallic disc being affixed to the positioning member. 
     
     
       10. A base for a fuel filter assembly comprising: a base member having a fuel supply inlet for receiving a flow of new fuel, a fuel supply outlet, an inlet plenum in fluid communication with the fuel supply inlet, an excess fuel inlet for receiving a flow of excess fuel, an excess fuel outlet, a fuel passage providing fluid communication between the excess fuel inlet and the excess fuel outlet, a wall separating the fuel passage from the inlet plenum, the wall defining an opening providing fluid communication between the fuel passage and the inlet plenum; and   a bimetallic disc disposed in the fuel passage adjacent the opening, the bimetallic disc having an edge portion;   wherein the new fuel has a pressure Pn and the excess fuel has a pressure Pe and a temperature Te, the edge portion of the bimetallic disc being flexed away from the wall to open the opening when the temperature of the excess fuel is below a predetermined value Tp, the edge portion of the bimetallic disc being flexed to engage the wall and close the opening when the temperature of the excess fuel is above the predetermined value Tp, the pressure of the excess fuel and the pressure of the new fuel defining a differential pressure across the wall, the differential pressure causing the excess fuel to flow from the fuel passage of the base member into the inlet plenum of the base member when the opening is open and preventing flow of new fuel from the inlet plenum of the base member into the fuel passage of the base member.   
     
     
       11. The base of claim 10 further comprising a check valve disposed in the fuel passage intermediate the opening and the excess fuel outlet. 
     
     
       12. The base of claim 10 wherein the opening comprises a throat having an outboard end adjacent said fuel passage and an inboard end adjacent said inlet plenum, the outboard and inboard ends each having a diameter, the diameter of the outboard end of the throat being greater than the diameter of the inboard end of the throat, wherein the throat has a chamfered interior surface. 
     
     
       13. The base of claim 12 wherein the bimetallic disc has an outside diameter which is greater than the diameter of the outboard end of the throat. 
     
     
       14. The base of claim 10 wherein the bimetallic disc and the wall of the base member define a gap when the edge portion of the bimetallic disc is flexed away from the wall. 
     
     
       15. The base of claim 10 further comprising a mounting plug having a body member and a positioning member extending to a distal tip, the bimetallic disc being mounted to the distal tip, wherein the mounting plug positions the bimetallic disc such that the bimetallic disc and the wall of the base member define a gap when the edge portion of the bimetallic disc is flexed away from the wall. 
     
     
       16. The base of claim 15 wherein the base member defines a mounting port disposed opposite the opening, the body member of the mounting plug being removably mounted in the mounting port. 
     
     
       17. A base for a fuel filter assembly comprising: a base member having a fuel supply inlet for receiving a flow of new fuel, a fuel supply outlet, an inlet plenum in fluid communication with the fuel supply inlet, an excess fuel inlet for receiving a flow of excess fuel, an excess fuel outlet, a fuel passage providing fluid communication between the excess fuel inlet and the excess fuel outlet, a wall separating the fuel passage from the inlet plenum, the wall defining an opening providing fluid communication between the fuel passage and the inlet plenum and the excess fuel having a temperature Te;   a positioning member extending into the fuel passage; and   a bimetallic disc having a center portion mounted to the positioning member, the bimetallic disc being disposed in the fuel passage adjacent the opening;   wherein the bimetallic disc is flexed to open the opening when the temperature Te of the excess fuel is below a first predetermined value Tp1 and the bimetallic disc is flexed to at least partially close the opening when the temperature Te of the excess fuel is above a second predetermined value Tp2.   
     
     
       18. The base of claim 17 wherein the base further comprises a mounting port and a mounting plug having a body member and a positioning member, the body member being removably mounted in the mounting port, the bimetallic disc being affixed to the positioning member of the plug. 
     
     
       19. The base of claim 17 wherein the bimetallic disc defines at least one orifice extending through the bimetallic disc, the orifice providing a flow path into the opening when bimetallic disc is flexed to close the opening. 
     
     
       20. The base of claim 17 wherein the opening comprises a throat segment adjacent the fuel passage of the base member, the throat segment defining at least one channel providing a flow path into the opening when bimetallic disc is flexed to close the opening. 
     
     
       21. The base of claim 17 wherein the opening has a diameter selected to provide a resistance to flow through the opening whereby a portion of the excess fuel flows through the excess fuel outlet when the bimetallic disc is flexed to open the opening.